I got a fabtech 6 inch lift put on about 3 months ago and sing then I have gone off-roading twice. Each time I get majorly stuck in small pits of mud. It seems as though my four wheel drive isn't working correctly since I only seem to have my rear wheels spinnign in the mud. My front drive shafts spins but the front tires dont. I have no idea whether this has to do with my transfer case or just a lack of power.

 

Check the vaccuum lines that run down to the front axle, make sure they are connected and that they are not leaking anywhere...had the same problem with my work truck a while back, turned out the vaccuum lines had come disconnected from the front diff and 4WD was not actually engaging, although the lights indicated it was...

 

Yep, I'll second that the front differential isn't being engaged. That's why you're not spinning the front wheels. You're basically offroading with a two wheeel drive truck. Check all the vacuum lines to the front diff and I'll bet you'll find one that's either leaking, disconnected or broken. You have more than enough power to spin the front wheels.--DIY